1. Field
Aspects relate to connectors for light-weight metal conductors, such as single or multiple stranded conductors, for example, aluminium conductors, which supply motor vehicle electrical consumers with electrical energy. Light-weight metal conductors of this type are also used for grounding electrical systems. Aspects also relate to method(s) for manufacturing a connecting element.
2. Discussion of Related Art
In motor vehicles, it has for a relatively long time been desirable, in order to save weight and also to substitute expensive metals with more economical alternatives, to make electrical conductors of light-weight metal, such as for example magnesium or aluminium or alloys thereof. Connections to these light-weight metal conductors present challenges, however. For example, in motor vehicles, dynamic loads over a long period of time (e.g. several years) and the tendency of the material to cold flow (even at low temperatures) reduces mechanical contacting forces in the connector, resulting in a poor electrical connection. An oxide layer, which can be present in particular on the surfaces of aluminium alloys, can also reduce the electrical conducting capacity through to the connector. Electrochemical corrosion in the region or interface between the connector and conducting wire can also reduce electrical conductivity. In this regard, connectors are conventionally made of nobler metals such as for example copper, and in the presence of electrolytes, maintaining an adequate connection is problematic. There has thus long been the need to provide improved connection to light-weight metal conductors.
U.S. Pat. No. 3,656,092 describes an aluminium line onto which an aluminium sleeve having a stepped internal diameter is placed in such a way that the end of the aluminium line abuts the steps within the aluminium sleeve. A copper contact element, having at its side facing the wire a sleeve having a complementary internal diameter, is slipped onto this aluminium sleeve. The aluminium sleeve and copper contact element are then connected by welding the two components.
U.S. Pat. No. 3,955,044 describes a connection element in which an aluminium line is connected to a copper contact element by slipping the contact element on the aluminium line and crimping the contact element to the aluminium line. During crimping, cold welding between the copper material of the contact element and the aluminium line occurs, at least in the region of the greatest deformation. The oxide layer present on the outside of the aluminium line is displaced during crimping.
U.S. Pat. No. 2,806,215 describes the electrical connection of an aluminium line to a copper contact element. An aluminium sleeve having a stepped internal diameter is slid onto the end of the aluminium line and subsequently welded to a complementarily shaped copper sleeve ending in a metal contact tab.
Cold welding of aluminium wires to copper sleeves slid onto the end of the wire is also described, by way of example, in DE 19 908 031 A1 and also DE 29 903 301 U1.
However, a common issue with all of these prior proposals is that they are unable to ensure a permanent electrical connection under dynamic loads and in the presence of electrolytes at the interface with the electrical connecting element. None of the prior proposals is able to counteract the above-mentioned problems that can cause the electrical connection fail under dynamic loads and in an environment generally supporting corrosion.